An AR15 in 6.5 Grendel would be fine with the guys I hunt with, or even a 6x45, .50 Beowulf or .30AR. However if you showed up with a .223 we'd probably send you home.
We've shot a lot of does and spikes with .223's during culling shoots (note it's not hunting, it's killing, sometimes 20-30 deer in one weekend) but we don't like them for regular hunts. If you shoot a good bullet and limit your shots to headshots or heart lung shots at 50-75 yards like our culls then they usually (but not always) work fine. But there are just to many ways for a .223 to not work the way it should so why take the chance or wounding the animal. Particularly if the range starts getting out to 125-150 yards, the wind is blowing a little, the angle isn't peferct, etc.
However I also know leases where most of the hunters are shooting .223's, so it depends on the group you hunt with.